The basic design concept for an alkali metal ionization detector has been disclosed in numerous prior publications and further has been described in detail in pending U.S. Pat. Applications Ser. No. 435,389 filed Jan. 21, 1974, entitled "A Sensor For Thermally Ionizable Particles And/Or Vapors", and pending U.S. Pat. Application Ser. No. 647,764 filed Jan. 8, 1976, entitled "Improved Filament For Alkali Metal Ionization Detector". Both of the above-identified pending applications are patent applications by the inventors of the subject application and both are assigned to the assignee of the present invention. These pending applications are incorporated herein by reference.
In the prior art type devices, as disclosed in the above-identified pending applications, the alkali metal ionization detector consists of a heated filament electrode also known as a thermal ionizer, and a collector electrode wherein the filament electrode is typically a wire and the collector electrode is a plate. The heated filament electrode thermally ionizes particles of interest in a gas and an electric field is established between the filament electrode and the collector electrode to cause the ions to flow to the collector electrode to produce an ion current which is an indication of the alkali metal concentration of the gas environment to which the heated filament electrode is exposed.
There is disclosed herein modifications to the electrode configuration as well as to the requirements for collector electrode electrical potential which enhance the usefulness of the conventional alkali metal ionization detector as well as minimizing the cost and complexity associated with the conventional implementation of the alkali metal ionization detector.